However, even before the attacks, interest wasn't high in the special election to fill the Senate seat John Kerry vacated when he became secretary of state. Voters will cast their ballots in both the Democratic and Republican primaries today and turnout is expected to be low.

"Certainly, it has been overshadowed in the sense that the drama and the pain of the April 15 bombing made it look less important but, on the other hand, no one was paying attention to [the special election] before the bombing," Tufts political science professor Jeffrey Berry said. "The race hasn't gained traction and this added to that. There was always going to be a tiny turnout anyway."

All five of the candidates suspended campaigning for the week after the bombings and have had to figure out the delicate balance since they started up again, but Berry chalked up the lack of interest not just to the bombings, but to election fatigue for Bay State residents, as well.

He added that there's a different feel than there was when Scott Brown beat state Attorney General Martha Coakley for an open Senate seat in 2010.

"There isn't the sort of anger out there like the last special election where we were at the bottom of the recession that propelled Scott Brown into office," Berry said, adding the third reason is a "dispirited" state Republican Party that lost both the 2012 Senate election, when then-Sen. Brown fell to Elizabeth Warren, and the 2010 gubernatorial election, won by Democratic Gov. Deval Patrick.

The electorate is largely undecided, according to polls, but the most recent survey done by Western New England University and MassLive.com taken between April 11 and 18 showed U.S. Rep. Ed Markey, D-Mass., ahead of U.S. Rep. Stephen Lynch, D-Mass., 44 to 34 percent.

As for the Republicans, the poll showed businessman and former Navy SEAL Gabriel Gomez with 33 percent, former acting director of the ATF and former U.S. Attorney Michael Sullivan with 27 percent and state legislator and Mitt Romney's former senior legal counsel Dan Winslow with 9 percent.

Dan Payne, a longtime political consultant and advisor to Markey, said the bombings "froze things the way they were," but it also changed the conversation from the economy to homeland security and national defense, with Lynch trying to "argue that Markey is soft on homeland security, but that hasn't really stuck."

Payne thinks the full stop the bombing put on campaigning hurt Lynch more than Markey's campaign.

"Lynch told the state party he had a two-week "Get Out the Vote" program," Payne said. "The first of those two weeks was the marathon bombing. That week was essentially wiped out. You couldn't make phone calls, you had to wait it out. So Lynch only had one week to conduct a GOTV program, while Markey lost a week. So losing a week didn't hurt him as much as Lynch."

He added that the Markey team will have 5,000 volunteers getting out the vote for Markey today. Berry, too, noted Markey's team was very "well organized."

Lynch rolled out an ad on focusing exclusively on the tragedy with no mention of the campaign besides for the required language at the end of the ad approving its message. He was the only candidate to do so.